View the Pre-Shared Key on an IPsec VPN tunnel-group

When troubleshooting VPN connectivity issues a common problem is a mis-matched pre-shared key.

When you add a pre-shared key to a tunnel-group if you issue a #sh run the output hides the key with a simple *. e.g:

tunnel-group 10.10.10.10 ipsec-attributes
 pre-shared-key *
 isakmp keepalive threshold 15 retry 2

To confirm precisely what has been applied (and therefore help confirm if both ends of your tunnel have the same key) use the following command:
 #more system:running-config

tunnel-group 10.10.10.10 ipsec-attributes
 pre-shared-key AbCdEfG192837645
 isakmp keepalive threshold 15 retry 2

Upgrade the IOS on a Cisco Catalyst 3750 switch

Steps to conduct an upgrade of the IOS are as follows:

1. Download the new image from www.cisco.com using a suitable account
2. Install a TFTP server such as SolarWinds TFTP Server (other TFTP programs are available)
3. Boot the switch and apply an IP address to the VLAN1 interface
4. Apply an IP in the same subnet to your PC/Laptop LAN port and cable up using a CAT5 straight through
5. Ping both sides to confirm connectivity
6. Copy the downloaded BIN image to the TFTP-Root folder you'll find on the C:drive
7. Start the TFTP Server on the PC/Laptop
8. On the switch back up the current image to your PC/Laptop #copy Flash:/[filename.bin] tftp
9. Enter the required remote host IP and confirm the destination file name when prompted
10. Allow the current file to copy over to the PC/Laptop
11. Once complete delete the original from the switch to create space for the new image #delete /recursive Flash:/[filename.bin]
12. Next copy the new image from the PC/Lpatop to the switch #copy tftp: flash:
13. Enter the remote host details and file name then confirm
14. Allow the file to copy
15. Set the new BIN as the system boot image #boot system flash:/[filename.bin]
16. write this #wr
17. Reload

Verify the image in use via - #sh ver

VPN - QM FSM error and PFS

We're busy attempting to bring up a site to site IPSec tunnel to Cisco router from our ASA.

Phase1 is completing but Phase2 fails with a 'QM FSM Error'.

This very unhelpful error message results from PFS not matching at either end. Either set it or don't set but if you have one end configured and the other not then you'll get an error like the one above.

Check the config on both ends of your VPN and either add PFS or remove by entering the following:
[no] crypto map VPNCONNECTION set pfs [group1 | group2 | group 5 ]

Notes:

• PFS must match at either end
• The default action on an ASA is to be off
• If you just enter 'set pfs' and don't define a group then group1 is offered by default and group1/group2 is accepted
• If you set the group then the same group must be returned by the remote peer.

Cisco CCDA - Done!

At the start of August I returned to the site of my last attempt and faced the Cisco CCDA once again.

This time I have re-read the OCG, read more from the Cisco Design Zone -
http://www.cisco.com/en/US/netsol/ns982/networking_solutions_program_home.html

I had also reviewed all the exam material I had and not take the results for granted (as I did last time).

What I found with my resit was that is was SOOOOOO much harder! really hard. I'm mean difficult hard. Hard.

Cisco must have a large pool of questions on this exam as I only spotted one question on the entire exam that I recognised from my first attempt and the rest were very detailed and narrow on the topic selection. As it is, I took my time, paced my self as best I could and finished with about 5 minutes to spare. last time I done a good chunk of the exam in the first 15 minutes.

I passed with a reasonable (not brilliant) mark and I'm just grateful I'm now looking at my new certificate on the desk partition in front of me.

My advise for the exam is truely go in depth. As much as you can, learn the detail, and ensure you know the 'Key Topic' sections of OCG of by heart. It's a tough exam but lays the foundation for the ARCH exam so I guess it has to be.

I'm picking the books up in October and hope to have my CCDP by Christmas. Lets see shall we...

Troubleshooting IPSec Phase2 issues

Problem - '#sh crypto ipsec sa' shows packets are being encrypted outbound but no packets are being decrypted inbound.

  Check the following: 

•     Crypto ACL at either end is a mirror of each other. Use host to host /32 addresses don't use subnets
•     Check routing at remote end is in place with correct exit interface
•     If traffic passes through a Firewall towards the VPN terminating peer check that NAT Traversal is in place - apply:

             policy-map global_policy
                 class inspection_default
                      inspect ipsec-pass-thru

•     Check that port 500/4500/ah/esp are permitted on outbound acls to the remote end. Look at ACL's.
•     Check that 'sysopt connection permit-vpn' is applied to permit IPSEC protocols to by pass ACLs that are applied to the tunnel interface

Off Topic - Spark's Laws

I decided I'd write down some of my musings. Nothing structured just observations from family life, work life and life in general.

Here you go:

Spark's Laws

#1 - Always tell the truth, that way you never have to remember anything
#2 - The smaller the child the bigger the splash they can make in the pool
#3 - The smaller the child the bigger the poo you have to clean up
#4 - If everyone did their job right first time, every time we could all have Fridays off.
#5 - You have to pay tax. Get over it.
#6 - The public can't handle the truth. - The truth is war is not nice but at times necessary to stand up for freedom. Taxes are not nice but pay for everything around you.
#7 - The media can't handle the truth. - They expect politicians to be honest but when one is honest and says 'Yes, I made a mistake' they hound them until they are forced to resign, instead of allowing them to learn, improve and move on. Is it any wonder Politicians lie? (and sports personalities for that matter)
#8 - Nature is cruel. Civilization, technology, and education does not change that.
#9 - Project deadlines are simply the date at which the project gets signed off, renamed, restarted and the PM gets their bonus regardless of what is achieved
#10 - If you want a project to run smoothly. Show the PM where the coffee machine is, close the door, and continue as normal.
#11 - The earlier in a project life cycle you implement your build the higher the certainty you'll have to back it out and rebuild it with 'new, unexpected' requirements that should have been captured right at the start.
#12 - The job's not done until you've finished the documentation.
#13 - In business, once you start copying the competition you've lost.
#14 - Spark's Law of Office Parties - Always make sure there is someone in a worse state than you...

I'll add more as I think of them.

Cheers.

CCDP - ARCH - Route filtering

Filter routes inbound to a router via a 'distribute-list' cmd to prevent inbound rutes from being learned.

Filter routes outbound to a neighbour via a 'redistribute [protocol] [process number] route-map FILTER' cmd and a deny statement on the FILTER route-map to stop routes from being advertised towards a neighbour.

CCDP - ARCH - Migrate Routing Protocols By Manipulating the AD

High level steps to move from one RP to another by manipulating the AD:
1) Configure the new RP and manually set the AD to be Higher (and therefore less preferred) than the current RP
2) Configure all devices as necessary and then check the topology using appropriate show commands
3) Ensure the new RP has all the required routes in its database
4) Either by increasing the AD on the current RP or by reducing the AD on the New RP change the AD so that the new RP is the preferred RP to use
5) Use show commands to ensure that the new RP is populating the routing table correctly (there shouldn't be any routes learned via the old protocol - if there are some then troubleshoot accordingly)
6) Remove the old RP from the routers
7) Move to normal running

CCDP - ARCH - UDLD (UniDirectional Link Detection):

• Used where there are fibre links between switches (but can also be applied to Copper interfaces)
• Interface could be seen as Up/Up but due to a mismatch on the tx/rx pairs the comms become unidirectional 
• UDLD Normal mode error-disabled the end that detected the unidirectional state - default mode
• UDLD Agressive mode disables both ends - set it with the [agressive] switch
• Uses 15 sec hello timer
• Can be applied globally or on the interface

CCDP - ARCH - STP tools

The following tools can be used to manage STP and L2 switching loops:

• PortFast: applied to a port connecting to an end user/host. Transitions the ports straight to forwarding
• UplinkFast: Offers L2 link load balancing, up to 5 secs convergence time once a link fails
• BackboneFast: Invoked when an inferor BPDU is received on a root port or blocked port. Reduces convergence times after an indirect failure.
• Loop Guard: Stops a bridging loop by preventing an Alternate port or Root port becoming a Designated port.
• Root Guard: Protects the Root switch by preventing other switches from taking the Root role.
• BPDU Guard: Apply to PortFast enabled ports. If the port recieves a BPDU the port gets shutdown
• UDLD (UniDirectional Link Detection): Detects when one-way connection exists on a copper/fibre link. Interface moves to a shutdown state and an alarm is triggered.
• Bridge Assurance: If a port that should receive BPDU's suddenly stops receiving them the port is moved to an 'Inconsistant' state and shutdown. Prevents potential loops